That's no moon! Spacecraft mistaken for new natural satellite

For 13 hours today, Earth had a new moon – or so we thought. Now astronomers have realised that an apparent small asteroid orbiting our planet is actually the European Space Agency's Gaia space telescope. The International Astronomical Union's Minor Planet Centre (MPC) in Cambridge, Massachusetts, keeps records of all the tiny space rocks in the sky and publishes new observations from around the world. This morning, MPC's Gareth Williams posted a description of 2015 HP116, seemingly an asteroid about a metre across that was spotted in a geocentric orbit by the Pan-STARRS telescope in Maui, Hawaii, last week. More

(Source: New Scientist - Apr 28)